A solvent is a substance, usually a liquid, in which solutes may be dissolved. In the case of cells, this is water. Other common solvents you may be familiar with include alcohol, acetone (commonly found in nail polish remover), and even air—remember gasses can be solutes also!
A solute is any substance dissolved in a solvent. In a cell there are many solutes, such as salts, sugars, and other small molecules. Simply put, a solute is the substance that is dissolved, and the solvent is the substance that does the dissolving.
Put the red blood cells in a hypertonic solution, and water will flow through the membrane out of the cells, since there is a higher solute concentration on the outside of the cells. As a result, the cells will become wrinkled and shriveled up!
A good model of a cell is a typical chicken egg—it has a shell on the outside, but remove that hard shell and it also has a semi-permeable membrane on the outside!
Here’s what you’ll need:
1. Two eggs (extras are appropriate, just in case!)
2. Two cups of vinegar
3. One 3-4 cup clear plastic cup or bowl
4. One large slotted spoon
5. Two small, wide mouthed drinking glasses
6. One cup of pure distilled water
7. One cup of corn syrup
NOTE: This experiment requires some planning ahead; preparing the eggs will take 24 to 48 hours.
Here’s what to do:
1. Place your eggs in the clear plastic cup.
2. Pour the vinegar over the top of the eggs.
3. Wait 24-48 hours for the vinegar to dissolve the egg shells! Look closely at the shells as they are dissolving in the vinegar—you should see small bubbles forming on the shell.
4. When the egg shells are fully dissolved, carefully remove them from the vinegar with the slotted spoon. Place one egg in each of the two drinking glasses.
5. Pour one cup of corn syrup over one of the eggs.
6. Pour one cup of distilled water over the other egg.
7. Allow the eggs to sit at room temperature for 3 hours to overnight.
8. Remove the eggs from their glasses with the slotted spoon, and place them carefully on the table.
What do the eggs look like? Has their appearance changed? If so, how? Based on this observation, which of these solutions is hypertonic? Hypotonic? Sketch the way the eggs look, and be sure to write down all your observations!
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